Eben Upton on Sinclair, Acorn, and the Raspberry Pi

Interview Inspired at least in part by Pi creator Eben Upton's dalliances with the home computers of the 1980s, the Raspberry Pi casts a long shadow over the retro computing world.

Upton, born in 1978, was given his first computer in 1988, just as magazine code listings were dwindling and game consoles were starting to dominate.

He recalls: "Before I was involved in it, there was a world of build-your-own-computers, the stuff where Acorn and Sinclair started off. And then you have that first wave of 8-bit computers.

"We talk a lot about the BBC Micro, because it's a machine that I had – it's a machine a lot of people had – but if you think about the actual impact, probably the Sinclair products are the ones that had more impact. They had more impact because they sold more units. And they sold more units because they cost less."

The Sinclair computers were famously built down to a price point and represented considerably better value for money in the UK than many of their rivals. However, it seems that with just a few more British pounds, the hardware could have been significantly improved.

Upton says: "There are always two philosophies in computer design. There are the design-to-featureset and design-to-price models. With Acorn, it has to be a design-to-featureset because the feature set came from the BBC. The Sinclair products were always design-to-cost, and probably overdesigned-to-cost in that they were frankly more focused on cost than was really necessary.

"We talk a lot when we're doing engineering about this idea of a knee and a curve, where you have some linearity up to a point. You can always get more performance, but you end up having to pull more cost and more engineering effort into designing the product to get [that] incremental performance.

"A lot of what we do at Raspberry Pi is about finding where that knee in the curve is."

Returning to the theme of Acorn and Sinclair, Upton continues: "You can see the Sinclair and Acorn products as being on either side. I don't think either of them hit the knee quite right. On one side, you've got the Sinclair product – if only they'd spent a tiny bit more money, it would have been amazing. And then you've got the Acorn product where probably you spent too much money on it and added features which are not relevant to anybody.

"Suppose you'd taken the Tube out. Would anybody have really cared?"

The Tube on the BBC Microcomputer was an expansion interface that permitted a second processor to be added. While we agree with Upton that the vast majority of users would have been unlikely to notice its omission, we have to acknowledge the importance of the interface during early development of the ARM processor.

The Raspberry Pi has become a powerhouse for retro computing applications. Implementations such as the PiStorm can give a huge performance boost to aging Commodore Amiga hardware, and the TIPI is a shot in the arm for Texas Instruments 99/4a users lacking the space or resources for a fully loaded peripheral expansion box. And, of course, there are applications for the diminutive computer for nearly every retro system in between.

Peter Onion of The National Museum of Computing told us that the team used a Pi for storage emulation on the museum's ICL 2966 mainframe to save wear and tear on moving parts.

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And then there is complete system emulation. Applications such as RetroPie have long existed to bring obsolete platforms and software to the Pi, and Upton notes that the Pi 5 should usher in more hardware emulation.

"It does bring in another generation, the Dolphin-era stuff. Not everything runs at speed, but you have a recognizable PlayStation 2, even before people put huge amounts of effort into tuning."

Dolphin is an open source emulator, first for the Nintendo GameCube and more recently the Wii.

The cost of a full-fat Pi is, however, creeping upwards. At the other end of the scale is the RP2040, a microcontroller that doubles as a low-powered computer and a home for the computers of yesteryear.

Upton ponders markets where having a PC is simply not an option.

"What I've always wondered – particularly for developing markets – is there a story about ultra-low cost? How useful is an 8086 DOS machine? And if I could make a 50-cent machine that is a PC XT, is that actually useful?

"You wonder if, for some of these markets, the choice between not having a PC at all or having a computer that has this huge back catalog of software ... what would I have as my first computer as a 10-year-old? Would I appreciate having a BBC Micro today? And is it better than if the choice is to have no computer?"

It's a good question. Is it better to have something retro, with a vast library of software, instead of nothing at all? While being able to bang out some Python on an inexpensive bit of hardware attached to the TV carries a certain allure, so too does the idea of being able to fire up something from decades ago with a huge number of software titles.

Although modern environments continue to expand their girth, there is something to be said for looking to the past. You could build something from scratch, as Upton observes, and you could also go for an emulator.

"What is that world?" he asks. "What are the platforms? Is that world PC XT? PC AT? Is that world Archimedes? Is there some point that lets you deliver a sub-dollar PC experience?"

Great things have been achieved with the full-fat Raspberry Pi. However, the lower-tier possibilities on offer from the RP2040 and its ilk are intriguing. Yes, you can run MicroPython on the device, but, as Upton posits, perhaps heading down the retro path might be a better option.

A modern computer with a single-digit dollar price tag emulating long obsolete hardware might seem retro to some users, but for others, it could represent a first entry into the world of computing. Just like Acorn and Sinclair did more than 40 years ago. ®